Possible Clues:

• 'Well hey there!'
• "Didn't expect to see you!"
• "Didn't think I'd see you here!"
• 'I wasn't expecting you!'
• "It's you!"
• 'Huh, didn't expect to see you here'
• "Surprised to run into you!"
• 'Huh, didn't see you there!'
• 'Huh, fancy seeing you here!'
• "Crazy to run into you here!"